47.5 MB - The Whole Building Design Guide

Safety of occupants is a significant concern with dry floodproofedbuildings. Regardless of the degree of protectionprovided, dry floodproofed buildings should not be occupiedduring flood events, because failure or overtopping of the floodproofingmeasures is likely to cause catastrophic structuraldamage. When human intervention is required, the people responsiblefor implementing those measures remain at risk whileat the building, even if a credible warning system is in place, becauseof the many uncertainties associated with predicting theonset of flood conditions.2.3.2 RISK REDUCTION IN “V ZONES”Flood hazard areas designated as “V Zones” on FIRMs are relativelynarrow areas along open coasts and lake shores where thebase flood conditions are expected to produce 3-foot or higherwaves. V Zones, sometimes called coastal high hazard areas or specialflood hazard areas subject to high-velocity wave action, arefound on the Pacific, Gulf, and Atlantic coasts, and around theGreat Lakes.Every effort should be made to locate critical facilities outside ofV Zones, because the destructive nature of waves makes it difficultto design a building to be fully functional during and after a floodevent. This is particularly true in coastal areas subject to hurricanesurge flooding (see Section 2.3.4). However, when a decision ismade to build a critical facility in a V Zone or Coastal A Zone, thecharacteristics of the site and the nature of the flood hazards mustbe examined prior to making important design decisions.Beach front areas with sand dunes pose special problems. Manmadealterations of sand dunes are not allowed unless analysesindicate that such modifications will not increase potential flooddamage. The site modifications described in Section 2.3.1.1 thatmay be used in some A Zones to reduce flood hazards generallyare not feasible in V Zones because of wave forces and potentialerosion and scour. In particular, structural fill is not allowed as ameans to raise a building site above the flood level.The NFIP and ASCE 24 do not allow use of dry floodproofingmeasures to protect nonresidential structures in V Zones.2-68 MAKING CRITICAL FACILITIES SAFE FROM Flooding